非处方药筛选中，要遵循疗效确切的原则，其含义包括

A．处方合理

B．功能主治明确

C．治疗期间不需经常调整剂量

D．经常使用不会引起耐药性

E．无"三致"作用

—What's the matter with you
—After the long walk, my leg （）and I couldn't go any further.

A. gave out

B. gave off

C. gave in

D. gave up